The present invention relates to valves and more particularly to one-way valves for draining entrapped air or gases from a vehicle hydraulic brake system.
It is not at all uncommon for the hydraulic brake system of an automobile to acquire a pocket of air. Typically, such air enters the hydraulic system when a leak develops either in the wheel cylinders or in the master cylinder and brake fluid is lost. Once the fluid level is lowered to a certain level, the master cylinder draws or pushes air into the hydraulic lines. The air accumulates in the wheel cylinders and the hydraulic system becomes ineffective. The air may be induced into the system when the master cylinder or wheel cylinders are rebuilt or replaced. In any case, when the air accumulates in the hydraulic system, it must be removed, otherwise the brakes will fail.
Bleeding of brake systems has in the past required either that two persons be present or else that one person repeatedly get in and out of the automobile. Wheel brake cylinders have a rotatable valve which is alternately rotated between a closed position and an open position during bleeding of a brake system. To remove air from the system the rotatable valve is opened and the brake peddle is depressed, creating pressure within the system thereby pushing air and/or brake fluid through the open rotatable valve. However, if the brake peddle is permitted to rise, without closing the valve, air is drawn back into the wheel cylinder and the purpose is defeated. If, on the other hand, the valve is opened, the peddle is depressed, the rotatable valve is closed, and the peddle returned to the upper position, a portion of air is effectively removed from the system. Thus, to bleed an automobile hydraulic brake system, the cycle of opening the rotatable valve, depressing the foot peddle, closing the rotatable valve, raising the foot peddle, opening the rotatable valve, depressing the foot peddle and again closing the rotatable valve has been necessary in order to bleed a brake system. In so doing, either two people must be present one operating the foot peddle, the other operating the rotatable valve or alternatively, one person must repeatedly move from the position of operating the rotatable valve and the position of depressing or raising the foot peddle. Such an approach for bleeding a brake system is time consuming and bothersome.
Some attempts have been made to overcome such problem. Some attempts have been directed toward including a permanently mounted one-way valve on the hydraulic cylinders. Certain problems have been encountered with such permanently mounted one-way valves. For example, such permanently mounted valves may accumulate foreign material over a period of time and thus remain closed when they are supposed to open or remain open when they are supposed to close. This necessitates disassembly of the wheel cylinder and replacement of the valve mechanism. Moreover, such permanently mounted valves are not adapted for ready attachment to existing hydraulic systems which have not been provided with such valving as original equipment. Illustrations of such permanently mounted valves are those shown in U.S. Pat. Nos. 2,046,228, 2,064,573, 2,069,606, 2,502,050 and 2,771,083.